barrett



(ModeL) J. A.'BARRBTT.

Pendulum. Attachment for Clocks.

No. 235,665. Patented Deci 21,1880.

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-PETERS. PHOTOMTHOGRAPHER. WASHINGTON. D C,

UNITED STATES PATENT OFFICE.

JOHN A. BARRETT, OE WOODSTOCK, VERMONT.

PENDULUM ATTACHMENT FOR CLOCKS.

SPECIFICATION forming part of Letters Patent No. 235,665, dated December21, 1880.

(ModeL) To all whom it may concern Be it known that I, JOHN ARNOLD BAR-RET'l, of Woodstock, in the county of \Vindsor and State of Vermont,have invented a new and useful Pendulum Attachment, of which thefollowing is a specification.

My invention relates to pendulums for use in controlling the movement ofclocks or any other machine, or for marking time.

The object of my invention is to attain a great degree of accuracy inregulating the rate of vibration of pendulums.

The form of pendulum now commonly used for this purpose consists of arod and weight so arranged that the weight may be moved up and down onthe rod, by which means the length of the pendulum may be varied and itsrate of vibration correspondinglyincreased or diminished. A practicaldisadvantage in this method lies in the difficulty of making thismovement of the weight upon the rod sufficiently slight to secure a highdegree of accuracy in the rate of vibration.

My invention consists in attaching to the pendulum, either to the rod orto the primary ball, a second or supplementary ball of less weight thanthe primary ball, and so arranged as to be carried up and down by anindependent movement.

The object of my invention is accomplished as follows: The desired rateis approximated by raising or lowering the primary ball. The rate isthen accurately attained by raising or lowering the supplementary ball.The advantage of this method arises from the fact that to accomplish agiven variation in rate the distance which it would be necessary to movethe supplementary ball is to the distance which it would be necessary tomove the primary ball in theinverse ratio of their specific weights. Forinstance, if the relation of the primary weight to the pendulum be one,and the relation of the supplementary weight to the pendulum beone-tenth, the supplementary weight must be moved ten times as far asthe primary weight in order to vary to an equal extent the rate ofvibration of the pendulum.

The accompanying drawings exhibit the invention claimed and apracticable method of applying the same.

Figure 1 is a front View of the primary ball in combination with thesupplementary ball, and shows a method of attaching it to the rod bymeans of a screw and nut. Fig. 2 is a side view of the same, and showsthe primary ball attached to the rod "and the supplementary ballattached to the primary ball.

a is the pendulum-rod. b is the primary ball. 0 and d are two armsextending at right angles from the rod (1. e is a wire passing throughholes in the arms 0 and d, and is bent at the upper end into an inverted-U form, and passes back through a second holein the arm 0, and.isthus prevented from having any motion except up and down in the line ofthe pendulum-rod. f is a thumb-nut fitted to a screw-thread on the wire0, and rests upon the arm (I, so that by turning it the wire 0 iscarried up or down together with the ball b. g is the supplementaryweight. It is a screw-wire, supported in the arms .9 and t in such a wayas to turn freely, and is fitted to an internal thread in the ball g.From the ball 9 a pin, 1', extends forward through a vertical slot, 0,in the primary ball I), so that the supplementary ball g has only avertical motion on the screwwire IL. The pin i is furnished at theoutside of the ball 1) with an index, m, which points to the scale a andmarks the movements and position of the ball g.

To regulate the rate of vibration ofthe pendulum, turn the nut f untilthe desired rate is approximated. Then attain the rate accurately byturning the screw h.

\Vhat I claim, and desire to secure by Letters Patent of the UnitedStates, is-

The supplementary weight in combination with pendulums, substantially asand for the purposedescribed.

JOHN ARNOLD BARRETT.

\Vitnesses:

JAMES C. BARRETT, HENRY F. FIELD.

